1. Field of the Invention
This invention generally relates to a component operating device for operating a hydraulic component. More specifically, the present invention relates to a bicycle hydraulic component operating device having a fluid reservoir tank in fluid communication with a hydraulic cylinder bore to form an open system type.
2. Background Information
In recent years, some high performance bicycles have been provided with hydraulic disc brake systems or other brake types of hydraulic brake system such as hydraulic shoe brakes. In the case of bicycles, the hydraulic brake systems are typically actuated by a brake lever that is attached to a bicycle handlebar. The brake lever is typically part of a brake operating device that attaches the brake lever to the bicycle handlebar. The brake operating device typically includes a master piston that is slidably disposed in a cylinder bore of a master cylinder, and which is actuated by the brake lever. The master cylinder contains a hydraulic fluid. The cylinder bore of the master cylinder is in fluid communication with a disc brake caliper housing in the case of a hydraulic disc brake via a fluid conduit. Brake pads of the disc brake caliper housing are typically spaced apart from a rotor by a predetermined gap. As the brake lever is operated contracted towards the handlebar), the master piston moves in the cylinder bore of the master cylinder to force liquid out of the master cylinder and into the fluid conduit connected to the caliper housing. The movement of fluid into the caliper housing causes the pistons in the caliper housing to move, and eventually brings the brake pads into contact with the rotor. Once the brake pads contact the rotor, they provide frictional resistance which can be increased by further operation of the lever. At this point, the caliper housing is fully pressurized, and further operation of the lever increases the system hydraulic pressure and frictional resistance applied to the rotor.